Fastener-applying implement



May 3, 1955 c. M. LINDsTRoM FASTENER-APPLYING IMPLEMENT 2 Sheets-Sheet 1 Filed June 2l, 1950 Il! IJ-en ifar llarlesMlzdshom by uw@ May 3, 1955 c. M. LINDsTRoM FASTENER-APPLYING IMPLEMENT 2 Sheets-Sheet 2 Filed June 2l, 1950 ifm L/g'arneys.

-III United States Patent M' FASTENER-APPLYIN G IMPLEMENT Charles M. Lindstrom, Westerly, R. I., assignor to Bostitch, Inc., Stonington, Conn., a corporation of Rhode Island Application June`21, 1950, Serial No. 169,318

8 Claims. (Cl. 1-187) This invention relates to an improved pneumaticallyoperated staple-applying implement for clinching the legs of preformed staples to form them into loops or rings with their legs overlapped in contiguous relationship for fastening various objects and articles in place.

More particularly, the invention relates to an imple- L holding a. supply of preformed staples fastened together in a stick or refill with means for feeding the staples to clinching means which forms them around the parts of the work.

Another object is to provide an implement of the type indicated embodying a pneumatically-operated piston for operating ythe clinching means with convenient manuallyoperable control-means for actuating the clinching means rapidly and positively in applying the staples to the work.

Another object is to provide in an implement of the type indicated, means for gripping a fabric to stretch it and hold it in place before the staple is applied, said means being adapted to gather the fabric together and to form it around an object simultaneously with the operation of the staple-applying means.

Another object is to provide a safety device to prevent accidental or unwarranted operation of the staple-applying means until manual release of the safety device.

Another object is to provide means for preventing partial release of the air-pressure to cause vibration or chattering of the pneumatically-operated mechanism when handling the implement.

Further objects of the improvement are set forth in the following specification which describes a preferred form of construction of the implement as illustrated in the accompanying drawings. In the drawings:

Fig. l is a plan view of the implement showing its manually-operable pressure-control means;

Fig. 2 is a side view of the same;

Fig. 3 is a bottom plan view of the implement showing the magazine for preformed staples;

Fig. 4 is a longitudinal sectional view of the implement on line 4-4 of Fig. 2 showing the staple-clinching means and the pneumatically-controlled piston for operating it;

Fig. 5 is a similar sectional view showing the pneumatically-operated piston at the end of its stroke for operating the clinching means;

Fig.'6 is a longitudinal `sectional elevation of the implement taken on line 6-6 of Fig. 1;

Fig.` 7 is a transverse sectional view of the implement takenon line 7--7 of Fig. 2;

Fig. 8 is a front view of the clinching jaws and their ICC means for seizing and gathering the fabric to which the staple is to be applied;

Fig. 9 is a detailed view in elevation of the forward portion of one of the clinching jaws showing its gripper means for gathering and holding the fabric;

Fig. 10 is an enlarged transverse sectional view of the rearward end of the implement taken on line 10--10 of Fig. 5; and

Fig. 11 is a detailed sectional view showing the arrangement of the nuts for fastening certain parts of the implement together at its forward end.

In a preferred form of construction the present improved implement comprises, in general, a longitudinallyextending magazine for containing preformed staples; a slidable cover on the magazine embodying a hollow core adapted for insertion through the staples to retain them in the magazine; a resiliently-actuatedl pusher slidable on the core for feeding the staples forwardly in the magazine; a pair of individually-pivoted jaws shaped to engage around the legs of the staple; and a pneumaticallyactuated piston for closing the ends of the jaws together to clinch the legs of a staple and form it into a loop or ring.

The piston for operating the clinching jaws is slidable in a cylinder arranged with its axis extending parallel with the staple-magazine and having an air-inlet at one end controlled by valve-means for admitting compressed air into the cylinder to slide the piston forwardly therein. The piston carries a tapered prow or wedge-shaped cam which is projected forwardly to engage between a pair of rollers on the jaw-members to separate their rearward ends and force their forward ends together to clinchthe legs of the staple into overlying contiguous relationship. The valve-means are operated by a hand-lever which is normally held inoperative by a safety device or catch that must be released by another finger of the hand before the valve-means can be operated to admit the air for sliding the piston.

The present implement is adapted to be held in one hand and operated in various positions, for example horizontally, vertically, or at different angles in relation to the work. As shown in the present drawings and for convenience of description it will be considered that the implement is disposed in horizontal position with the staple-magazine at the bottom, the pneumatic cylinder overlying it at the top and the means for operating the jaws also superimposed above the magazine, see Figs. 2 and 7.

Referring to Fig. 7 of the drawings, the magazine 2 ofthe implement is preferably constructed of sheetmetal formed into inverted trough-shape in cross-section with a relatively flat upper wall 3 and arcuatelyshaped sides 4 conforming to the shape of the staples to be used in the device. It will be understood that the staples s are of a type in general use having a straight or slightly arched head with legs connected thereto by curved portions of relatively large radius` and continued in straight portions depending in angular or inclined relation to each other.

A sheet-metal cover 5 for the magazine of troughshape has a at bottom, outwardiy-inclined sides and anges at the top of the sides folded around `to form grooved runners 6 adapted to engage with and slide `on laterally-projecting ribs or flanges 7 on the magazine 2. The cover 5 is thus adapted to be withdrawn by sliding it rearwardly along the magazine 2 to open the latter for insertion of a supply of staples thereinto; the staples s being usually joined together ibyan adhesive in a stick or refill-for convenience in packaging and handling them in groups. The staples s are retained within the magazine 2 by means of a hollow core 10 inserted through the whole series of staples in the stick by sliding the cover Patented May 3, 1955l 5 forwardly on the magazine. As shown in Fig. 7, thc core has a flat base welded or otherwise fastened to the at bottom wall of the cover 5 with slides 11 folded upwardly therefrom at divergent angles and flanges 12 bent inwardly at the top.

The means for feeding the staples forwardly in the magazine 2 t0 position the foremost one between the jaws of the implement may be of usual construction consisting in a pusher 15 having a head 16 shaped to overlic the core 10 and straddle its sides. The pusher 15 is provided with a relatively narrow tail-piece 17 projecting rearwardly therefrom and bent downwardly at its end in a portion 18 engaging through a longitudinally-extending slot 19 in the top of the core 10. A helical spring 20 enclosed within the sides of the core 10 is arranged with its rearward end abutting a vertical plate 2l, sec Fig. 6, in the end of the core and its forward end bearing against the down-turned end portion 18 of the pusher 15 for sliding it on the core. The plate 21 forms an abutment for the end of the spring 20, being held in slots in the inturned flanges 12 on the core 10 and fastened in place by means of a screw 22 having itshead set up against the end of the core. It will be understood that when the cover 5 is slid forwardly on the magazine 2 the head 16 of the pusher 15 will be carried against the end of the stick of staples s and continued movement of the cover will contract and load the spring 20 to adapt it to function to feed the staples forwardly to the forming or clinching jaws. The cover 5 and its attached core 10 are latched in operative position on the magazine 2 by manually-releasable means as next described.

A catch or detent-mernber 25 constructed of folded sheet-metal is welded or otherwise fastened to the top wall 3 of the magazine. The catch 25 is formed with sides folded downwardly from its upper portion and terminating in shouldered portions providing projections 27 with curved or tapering edges. A finger-operable latch 30 (Fig. 10) constructed of springmetal is shaped at its rearward end to underlie the core 10 and enclose its sides with laterally-projecting wings bent upwardly to overlie the sides of the magazine 2. The latch 3i) is provided with a tail-portion 31 riveted to the bottom wall of the core 10 at 32 to adapt it to act as a leafspring for maintaining the latch engaged with the shoulders on the detent-portions 27 of the catch 25. As shown more particularly in Figs. 2 and 3, the rearward portion of the latch 30 extends across the bottom of the core 10 and is then folded upwardly at its sides and extended laterally in the wings 33 adapted to engage the shoulders of the detent-portions 27 of the catch 25. Through this engagement of the latch-member 30 with the detent-shoulders on the catch 25 the core it) may be locked in position with its fore portion inserted through the whole series of staples s to retain them in the magazine; the latch being manually releasable from the detent-shoulders to allow retraction of the cover 5 and core 10 whereof to open the magazine for the insertion of the staples. A screw 34 passing through a hole in the top of the magazine 2 and through a hole in the catch 25 projects downwardly therefrom for engagement with the end portion 18 of the pusher 15 to prevent complete withdrawal of the cover 5 and core 10. A lug or finger 36 projecting forwardly from a plate 35, later described as overlying the magazine 2, see Fig. 6, serves as a detent or stop to prevent the staples being ejected from the forward end of the core 1t) and also serves to locate the foremost staple in alinement with the grooves in the clinching jaws, also to be later described.

The magazine 2 has suitably attached thereto, by welding or otherwise, a flat plate of greater thickness than the top wall of the magazine, this plate forming a base or support for the clincher-jaws 40 at the forward end of the implement. The plate 35 also forms abase for mounting the cylinder 60 in which the piston for the jaws operates. Referring particularly to Figs. 4, 5 and 6, the two jaws 40 are constructed of relatively thick, hardened metal and pivoted on individual studs 42 riveted through the plate 35 to project upwardly therefrom. The studs 42 are reduced in diameter above the jaws 40 to form shoulders supporting a pair of overlying plates 43 and 44. The two plates 43 and 44 are held down against the shoulders on the studs 42 by means of relatively long nuts 45 screwed onto the upper threaded portions of the studs as shown more particularly in Fig. 1l, it being understood that the bottom plate 43 overlies the top of the jaws 40 with a clearance therebetween so that the latter will pivot freely on the studs 42.

Each nut 45 (Fig. 1l) terminates at the top in a reduced screw-threaded portion which projects through a relatively thin sheet-metal cover or shield 51 fastened in place by nuts 52 screwed down thereagainst. The cover or shield 51 is of tapering shape in plan view as shown in Fig. l with inclined sides folded downwardly therefrom and a forward wall of less height. The cover 51 overlies and encloses the pivoted jaws 40 and their operating mechanism to be later described. At its rearward end the top wall of the cover 51 is provided with a projecting lip 53, see Fig. 3, which is inserted into slots 54 at the forward end of the cylinder 60 to`assist in holding it in place. In Figs. 4 and 5 of the drawings the cover 51 is shown in section to more clearly illustrate the construction of the jaws 40 and their operating mechanism next described.

Each clincher-jaw 40 has a depending portion 41 at its forward end, see Fig. 9, formed with a recess 46 adapted to receive one of the legs of a staple prior to bending the legs into overlying relationship when the jaws are closed together. The groove or recess 46 may be staked or milled into the depending portion 41 lof the jaw. The lower end of the projection 41 on each jaw 4Q is formed at the front to provide a sharp-pointed prong 47 adapted to engage through the fabric or other part to be stapled to hold it in place and also, in the case of fabrics or other flexible materials, to act in cooperation with the opposite jaw to gather the material together. At the rearward end of each jaw 40 is a stud 49 riveted therethrough and projecting upwardly therefrom with a roller 5t) held rotatively on4 its reduced upper portion. The rollers 50 serve as the means for operating the jaws 40 to cause them to pivot on ytheir studs 42 with their forward ends closing together to clinch the legs of the staple into the form of a ring or loop. For this purpose a wedge-shaped cam is slidy forwardly between the rollers 50 by the action of the piston 56 in the cylinder 6 under pneumaticpressure. When the piston 56 is forced forwardly the pointed prowkof the cam 55 is entered between the two rollers 50 to swing the rearward ends of the jaws 40 apart and force their forward jaw-portions 41 toward each other in the manner indicated in Figs. 4 and 5. A helical spring 57 arranged with its ends held in pockets 58 in the adjacent faces of the jaws 40 at their forward ends normally tends t0 move the jaws apart and adjust the rollers 50 toward each other.

The plate 44, previously referred to, is formed with a rearwardly-directed pointed portion 59. The inclined edges of the pointed portion 59 of the plate 44 are arranged to engage against the peripheries of the studs 49 on which the rollers 50 are journaled to locate the rollers in proper relation for alining the forward ends of the jaws 40 with the staples fed thereto. ln order to adjust the jaws in their lateral relationship the plate 44 is adapted to be moved forwardly or rearwardly to alter the relationship between the rollers 50. For this purpose the plate 44 is providedwith slots 48 through which the threaded ends of the studs 42 project and by releasing the holding nuts 45 the plate 44 may be moved in one direction to force the rollers apart to close the forward p ends of the jaws toward each other; or moved in the opposite direction to cause the rollers to move toward each other for providing wider spacing :between the jaws. The pointed end 59 of the plate 44 also acts to aline the adjacent peripheries of the rollers 50 with the leading apex end of the cam 55.

As shown in Figs. 4 to 6, inclusive, the piston 56, which may be of any preferred construction, has a head 61 at its end constituted by a pair of washers 62 and 63 overlying a flexible cup-shaped member 64 constructed of leather or other suitable material with its rim engaging the bore of the cylinder 60. The cam 55 is formed as a substantially flat projection at the end of a stem 65 connected to and extending forwardly from the piston 56. The stem 65 is formed with a screw-threaded neckportion 66 inserted through the washers 62, 63 and 64 with a nut 67 tightened against the washer 63 to fasten the parts in connection. The stem 65l is formed with a longitudinal slot 68 through which a pin 70 engages to guide the stem as the piston is slid forwardly in the cylinder 60. The pin 70 may be formed with a reduced threaded portion 71 screwed into the base-plate 35 to fasten it in place with its upper end projecting through a hole in the top of the cylinder 60. A helical spring 75 encircles the stem 65 of the piston 56 and when the latter is advanced to close the jaws 40 together the end of the spring engages the pin 70 to cause the spring to be compressed and loaded whereby it will react to return the piston to first position after the air-pressure in the cylinder 60.is relieved. As the piston 56 is retracted in the cylinder 60 to withdraw the cam 55 from between the rollers 50, the spring 57 will react to open the jaws 40 and engage the studs 49 against the edges of the pointed end 59 of the plate 44 to locate the rollers with their adjacent peripheries in alinement with the apex of the cam.

The rearward end of the cylinder 60 is closed by a head or member 76 formed with a boss 77 on its rearward end having a threaded bore 78. Screwed into the bore 78 is a nipple `79 formed with an outer threaded-portion to which may be attached a hose for supplying compressed air to the cylinder. A duct 80 leads from the nipple 79 into a transverse-bore 81 in the member 76 which communicates with a larger transverse bore 82 having a passage 83 extending axially into the interior of the cylinder 60. Screwed into the transverse-bore 82 from the side of the closure-'member 76 is a plug 84 having its .head 85 set up against a shoulder at the end of 'the bore. The plug T84 is provided with an axial bore 86 of somewhat smaller diameter than that of the bore 82.

The valve-closure means comprises two balls 89 and 90 of different diameter, the larger one 90 being free to move `in the main bore 82 to close its inner end at the inlet port; while the smaller one 89 is `adapted to close the outlet port at the end of the bore 86 in the plug 84, see Figs. 4rand 5. The ball 89 is smaller than the ball 90 in order to provide `sufficient space `in the bore 82 for the air to exhaust rapidly through the `port at the end of the bore 86 in the plug 84. Normally, the larger ball90 is engaged with the inner end of the bore 82 to close the inlet port and prevent the air from entering the cylinder 60 through the nipple 79, see Fig. 4, 'being held in this relationship under pressure of the smaller ball 89 actuated 'by a screw-threaded pin .91 slidable in the bore 86 of the plug 84. The pin 91 is fastened to a handlever 95 by means of nuts 92 set up against the sides `of the upwardly-projecting ear at the end of said lever, see Fig. 2. The hand-lever 95 is of U-shape in cross-section having lateral anges folded `at right-angles to straddle a bearing 96 projecting from the side of the base-plate 35. A screw 97 threaded through one lateral flange of the lever 95 and journaled in the bore of the bearing 96 forms a pivotal mounting for the lever. The end of the lever 95 opposite from that carrying the `pin 91 terminates in an outwardly-extended curved finger-rest for convenience in operating the lever with the thumb or fingers of the hand. A helical spring 9.8 attached t a lug 99 punched out and bent inwardly from the lever 95,`

see Fig. 5, extends forwardly therefrom with its opposite end fastened to a latch-lever 100 which functions similarly to the sear or safety-catch of a pistol or gun for holding the trigger cocked to prevent it from ring.

The latch-lever 100 is constituted as the safety-catch for preventing unwarranted or accidental movement of the operating lever until the latch-lever is released by finger pressure on the opposite side of the implement. The latch-lever is pivoted on a stud 101 having a shouldered end portion with a screw-threaded shank 102 screwed through the base-plate 35, see Fig. 6, to fasten it thereto within a cut-out recess 103 at the end of the cylinder 60. The latch-lever 100 has a curved end in the form of a cam adapted to slide along the forward curved end of the lever 95 to sustain the latter in inoper* ative relationship as shown in Fig. 4. The opposite end of the latch-lever 100 projects outwardly beyond the opposite side of the cylinder 60 and is bent downwardly to terminate in a curved projection 104 in convenient position for engagement by the operators finger. By pressing on the finger-piece 104 the latch-lever 100 may be rocked into the position shown in Fig. 5 against the tension of the spring 98 to release the hand-lever 95 and permit it to withdraw the plunger-pin 91 so that the balls 89 and 90 may be moved to open the inlet port at the end of the bore 82. Operation of the hand-lever 95 in this manner will admit air-pressure into the cyl- Iinder 60 to actuate the piston 56 as more particularly explained hereinafter in connection with the method of operation of the complete implement.

The present implement may be operated by holding it in the hand in any convenient manner; for example, with the palm of the hand overlying the cylinder 60, the thumb extended across the end of the handalever 95 and the forefinger pressed against the finger-piece 104 of the latch-lever 100. The latch-lever 100 is first rocked to release its cam-shaped end from the hand-lever 95 so that the latter can be pressed inwardly by the thumb to open the air-valve. As the lever 95 is pressed inwardly the plunger-pin 91 will be withdrawn to admit compressed air through the nipple 79 and into the main bore S2 as the balls 89 and 90 are moved into the position shown in Fig. 5 of the drawings. With the balls in this relationship the smaller ball 89 is pressed against the end of the bore 86 in the plug 84 to close the outlet port and prevent the escape of air therethrough. The air is allowed to circulate around the larger ball 90 and ow through the passage 83 to enter the interior of the cylinder 60 and act against the piston 56.

The piston 56 is slid forwardly under pressure of the air in the cylinder 60 to force the wedge-shaped cam 55 between the two rollers 50 at the ends of the jaws 40. The rearward ends of the jaws 40'Will thus be swung apart to close their forward ends against the foremost staple s in the magazine 2, see Figs. 5 and 6. Continued pressure of the cam 55 against the rollers 50 will cause the depending portions 41 of the jaws 40 to bend the legs of the staples s inwardly toward each other and into con tiguous overlapping relationship to form a loop or ring enclosing the part of the work to be fastened in place. Prior to forming the staple, the pointed prongs 47 on the jaws 40 may be engaged with the fabric or other material to be stapled and as the jaws move together to clinch the legs of the staple the material is gathered or puckered so as to conform to the interior of the staple and overlie the part to which it is fastened. In this way an extremely neat and self-conforming connection is made between the material and the rod or other element of the frame to which it is attached, thus effecting an important improvement in the method of operation of the present implement.

After each staple is clinched in place pressure on both levers is released so that the spring 98 will rock `the latchlever 100 back into the position shown in Fig. 4 and its cam-shaped end will force the forward end of the handlever 95 outwardly to rock its rearward end inwardly. The plunger-pin 91 will then be projected into the bore 86 of the plug 84 to shift the balls 89 and 90 back into first position and close the air-inlet port at the end of the bore 82. When the pressure of the air is shut off in this manner the spring '75 acts to retract the piston 55 and force the air through the bore 83 to exhaust it through the bore 86 in the plug 84. The retraction of the piston 56 withdraws the cam 55 from between the rollers 50 and the two jaws 40 are returned to open position under the tension of the spring 57 at their forward ends. The implement may be operated continuously with the staples s feeding forwardly under the impulse of the pusher 1S advanced by the spring 20. The staples are thus fed along the core 10 in the magazine 2 to carry each forcmost one into position between the depending portions 41 of the jaws 40.

It will be observed from the foregoing specification that the'present invention provides an implement that is most convenient to operate for forming staples into loops or rings to attach fabric and other materials to frames, or for other purposes such as binding together the meshed wires of fencing, screens and the like. Besides being convenient to operate and positive in action the present implement is protected against accidental or unwarranted actuation by the safety device which must be released manually before the hand-lever can be operated. As an added feature of improvement the clinching jaws are provided with pointed prongs for engagement with the fabric so that the prongs move toward each other simultaneously with the closing of the jaws to gather the fabric around the article to which it is to be fastened.

While the invention is herein described and illustrated as embodied in a preferred form of construction it is to be understood that changes may be made in the structure and method of arrangement of the parts of the device without departing from the spirit or scope of the invention as expressed in the following claims. Therefore, without limiting myself in this respect, I claim:

l. In an implement of the type indicated having a pair of pivoted jaws provided with clinching portions at their forward ends movable toward each other, rollers journaled on studs projecting upwardly from the rearward ends of the jaws, a wedge-shaped cam engageable with the rollers to close the forward ends of the jaws to clinch the legs of a staple, a cylinder, a piston slidable in said cylinder to actuate the cam, and manually-operable means for admitting compressed air to the cylinder to slide the piston, the combination therewith of means for adjusting the lateral relationship of the rollers to regulate the distance between the forward ends of the jaws to properly aline them with the staples t'ed thereto from a magazine, said adjusting means comprising a V-shaped member having inclined edges adapted to engage between said studs on which the rollers are journaled, and means to fasten said tl-shaped member in different positions of adjustment with its inclined edges engaging at varying distances between said studs whereby to regulate the relationship between the opposite jaws to valy the relative position of their forward ends.

2. In an ,implement of the type indicated having a pair of pivoted jaws adapted to swin g towards each other to clinch a staple held therebetween, studs at the rearward ends of the jaws, rollers journaled on said studs, a cylinder, a piston slidable in said cylinder, a wedge-shaped cam slidable by the piston to enter it between the rollers and swing the jaws to close their forward ends against a staple, and a manually-controlled valve for admitting air to the cylinder to slide the piston, the combination therewith of a V-shaped member having its inclined edges engageable with the studs of the rollers to locate the latter in relation to each other, and means for adjusting said V-shaped member longitudinally with respect to the studs to advance its inclined edges to a greater or lesser extent between the studs of the rollers to thereby regulate the width of the opening between the forward ends of the jaws, and means to xedly secure said V-shaped member in its different positions of adjustment.

3. In a stapling implement comprising a pair of pivoted members having jaws at their forward ends for clinching the legs of a staple with means engageable at their rearward ends for pivoting said members, and a wedge-shaped member slidable to engage the means at the rearward ends of said jaw-members to force their jaws against the legs of a staple, the combination therewith of a slidable cam-shaped element adapted to engage said means at the rearward ends of the jaw-members to pivot said members for adjusting their jaws to initially regulate the spacing therebetween, and means for fastening said adjustable element in position to maintain the jaws in adjusted relationship.

4. In a stapling implement comprising a pair of pivoted clincher-members having jaws at their forward ends for clinching the legs of a staple with means at their rearward ends engageable for pivoting said members to force their jaws against a staple entered therebetween, and cam-means movable for engaging said means at the rearward ends of the jaw-members for actuating said members, the combination therewith of an adjusting element slidable between the rearward ends of said pivoted members to initially position said members with their jaws in predetermined spaced relationship for receiving a staple, and means for fixedly retaining said adjusting element in adjusted relationship.

5. In an implement of the type specified comprising a pair of pivoted members having opposed jaws at one 1 end for clinching the legs of a staple with means at the opposite ends of said members displaceable for pivoting said members, and means movable between said displaceable means for actuating said jaw-members to force their jaws against a staple, the combination therewith of a slidable adjusting element having cam-means for engaging said displaceable means at the rearward ends of the jawmembers lto initially adjust their jaws in spaced relationship for receiving a staple therebetween, and means for fastening said adjusting element in xed position to maintain the jaws of said members in proper spaced relationship for receiving a staple.

6. In an implement of the type indicated having a pair yof pivoted jaw-members shaped at their forward ends for engaging and clinching the legs of a staple positioned therebetween and a movable cam-member engageable between the rearward ends of said jaw-members 'to actuate said members for forcing their jaws against the staple, the combination therewith of an element slidable between the rearward ends of said jaw-members to adjust them with their jaws in proper spaced relationship to receive a staple, and means for fastening said slidable element in fixed position for initially holding the jaws of said members in spaced-apart adjusted relationship.

7. In an implement of the type indicated comprising a pair of jaw-members pivotally mounted to adapt their jaws to be moved toward each other for clinching the legs of a staple received therebetween with means engageable at the rearward ends of said members for pivoting them, and means movable between said engageable means at the rearward ends of said jaw-members to force their jaws against a staple, the combination therewith of a slidable adjusting element for engaging the means at the rearward ends of said jaw-members to set their jaws in proper spaced relationship for receiving a staple therebetween, and means for fastening said adjustable element in fixed position to retain the jaws in adjusted relationship.

8. In an implement of the type indicated comprising a pair of members pivoted together intermediate their ends and formed with jaws at one end for clinching the legs of a staple, with studs on the opposite ends of said jaw-members engageable for forcing their jaws against a staple held therebetween, and means engageable with said studs for actuating said jaw-members, the combination of a manually-adjustable element having cam-shaped means for engaging the studs at the rearward ends of said jaw-members to adjust their jaws in proper relationship for receiving a staple therebetween, and means for fastening said adjusting element in position to maintain the jaws in adjusted relationship.

References Cited in the le of this patent UNITED STATES PATENTS Maliha Nov. 21, 1916 Lundblad Aug. 7, 1923 Palrngren Feb. 11, 1930 Forss Mar. 12, 1946 Powers Nov. 8, 1949 

